<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link rel="stylesheet" href="./css/dl.css">
  <title>Document</title>
  
</head> 
<body>
  <div class="bg">
  <div class="center">
    <div class="login">
      <h4>登录界面</h4>
      <input type="text" class="username" placeholder="请输入用户名">
      <span>用户名不能为空！</span>
      <input type="password" class="pwd" placeholder="请输入密码">
      <div class="check">
        <input type="checkbox" id="yes">
        <label for="yes">记住密码</label>
        <a href="">忘记密码</a>
      </div>
      <button>登录</button>
    </div>
  </div>
</div>
</body>
</html>